Most organisms cannot use nitrogen from the atmosphere for their needs. However, certain soil bacteria, as well as bacteria that live on the roots of certain plants, can "fix" nitrogen; that is, they convert nitrogen into ammonium and nitrate compounds.
Other plants use these simple nitrogen compounds to make proteins and other complex nitrogen compounds.
Animals eat these plants, and other animals eat those animals, Finally bacteria in decaying organic matter convert the nitrogen compounds back to nitrogen.
In this way, nitrogen in our environment continually cycles from notrogen to living organisms and back.
Nitrogen is produced from atmospheric air. The air is liquified by compression and cooling and liquid nitrogen is separated from other components by distillation.
Since nitrogen is the most volatile component of liquid air, so it is the first to be distilled off, leaving behind a liquid that is primarily oxygen with a small amount of noble gases (mostly argan).
Liquid nitrogen is used as a refrigerant to freeze foods, biological materials and in laboratory to achieve low temperature for conducting experiments. The other principal use of nitrogen is to prepare nitrogen compounds.
1. Ammonia (NH3) is the most important commercial compound of nitrogen. It is a colorless gas with a characteristic irritating or pungent odor. It is prepared commercially from N2 and H2 by the Haber process.
Ammonia can be easily liquified and the liquid is used as a fertilizer. Ammonia salts, such as the sulfate and nitrate, are also used as fertilizers. Large plants convert ammonia into urea, NH2CONH2, which is used as fertilizer, livestock feed supplement, and in the manufacture of formaldehyde plastics.
Ammonia is also the starting compound in the manufacture of other nitrogen compounds.
2. Nitrous oxide, N2O, is a colorless gas with a sweet odor. It is also known as laughing gas, and is used as a dental anesthetic.
3. Nitric oxide, NO, is a colorless gas. Nitric oxide reacts rapidly with oxygen to give nitrogen dioxide.
4. Nitric acid, HNO3, the third most important industrial acid (after sulfuric acid and phosphoric acid) and is a strong oxidising agent. It is used in the preparation of explosives, nylon, and polyurethane plastics. It is produced from ammonia usinfg the Ostwald process.